Sql update set replace all like where like

First post.

In a table called 'customers' I want to replace all the firstnames that begin with 'A' with 'Afirstname'; resulting in 'Adam', 'Alan', 'Anita', 'Anna', 'Anuska', etc. getting the firstname of 'Afirstname'.

It's a table from a company database I have copied to my own laptop so I can run some tests on in, but for data protection purposes I need to render the actual user information anonymous - without destroying it so much I can't use it. Makes sense?

Getting assistance from another source I have a solution to it. It seems I was, both making a more complicated query than necessary, and not understanding properly what REPLACE needs. The solution that works for me is this:

UPDATE customers SET firstname = 'Afirstname' WHERE firstname LIKE 'A%'﻿